1. Field of the Invention
The present invention relates to a mounting structure for distance measuring sensors provided at the front of an automotive vehicle.
2. Description of the Related Art
In measuring a distance between the subject vehicle and a vehicle running or obstacle existing ahead of the subject vehicle by detecting the vehicle or obstacle, since it is not a close distance that is to be measured, a method is adopted which utilizes a triangulation in order to measure the distance accurately.
Consequently, distance measuring sensors need to be disposed on at least two positions, a distance between which is known for a required measurement. And, in view of the distance measuring performance, the longer the distance between the two positions becomes, the more accurate a resultant measurement becomes. An example of such a distance measuring sensor placement is disclosed in JP-A-7-125567.
In the example, a CCD camera is used as a distance measuring sensor, and two CCD cameras each installing into its body, electronic components such as an image circuit board and a diaphragm circuit board are provided at positions apart from each other by a predetermined distance.
Unless the relative position between the two CCD cameras is maintained, no high-accuracy distance measurement can be expected. However, there is disclosed in the example no description of a distance measuring sensor mounting structure which can secure the accuracy of the relative position of the two CCD cameras.
The invention was made in view of the situation, and an object thereof is to provide a distance measuring sensor mounting structure which can not only maintain the high accuracy of a relative position between two distance measuring sensors while the sensors keep a required relative distance between them but also increase the rigidity of the body of a vehicle.
With a view to attaining the object, according to a first aspect of the invention, there is provided a distance measuring sensor mounting structure wherein at least two sensor brackets each having a distance measuring sensor fixedly supported thereon are provided at predetermined positions on an automotive body frame structure in such a manner as to extend between a bulkhead upper frame and a front bumper beam situated below the bulkhead upper frame diagonally to the front to connect the bulkhead upper frame to the front bumper beam.
The bulkhead upper frame and the front bumper beam are respectively directed transversely and joined to the body of a vehicle to form a strong structure which constitutes the front of the body.
Since at least two sensor brackets are provided to extend between the bulkhead upper frame and the front bumper beam which are disposed in parallel to each other, the rigidity of the overall structure can be increased, whereby the improvement in rigidity of the body of the vehicle can be attained.
In addition, since the distance measuring sensor is fixedly supported on each sensor bracket which constitutes the highly rigid structure, the high accuracy of the relative position of the distance measuring sensors can be secured, enabling a highly accurate distance measurement.
Furthermore, since the distance measuring sensors are fixed to the sensor brackets which are provided to extend between the bulkhead upper frame and the front bumper beam, the distance measuring sensors can be disposed to face the front grille without disposing therebetween any obstacle such as glass which would deteriorate the performance of the sensors.
According to a second aspect of the invention, there is provided a distance measuring sensor mounting structure as set forth in the first aspect of the invention, wherein the sensor bracket comprises a bottom plate and a back plate which are disposed to form an L-shape as viewed from the side, wherein a rib is formed on the sensor bracket in such a manner as to connect the edge of the bottom bracket to the edge of the back plate, and wherein the bottom plate is fixedly attached to the front bumper beam whereas the back plate is fixedly attached to the bulkhead upper frame.
Since in the sensor bracket the ribs connect together the edges of the bottom and back plates which are formed into the L-shape, the rigidity of the sensor bracket itself is improved, whereby the mounting strength of the distance measuring sensor can be maintained much higher.